Automobiles with internal combustion engines (IC engines) which use gasoline or diesel as main fuel significantly affect on environmental pollution such as air pollution. Thus, there has been a great effort on development of electric or hybrid vehicles in order to reduce environmental pollution.
Recently, high power secondary batteries using non-aqueous electrolyte with high density energy are under development. A secondary battery with a large-volume is formed of multiple high power secondary batteries in serial connection to be used in a device such as an electric vehicle that requires high power for driving a motor. Therefore in general, one large-volume secondary cell, which is called “battery” hereinafter, is formed of multiple secondary batteries in serial connection.
Especially for batteries for Hybrid Electric Vehicle (HEV), several or sometimes several hundreds of secondary cells are recharged and discharged in turn and it needs to make batteries keep the optimum status by controlling recharge-discharge systems.
For this, a Battery Management System (BMS) is provided to control overall conditions of the battery. BMS estimates System-on-Chip (SOC) through operation by detecting voltage, current and temperature of batteries, and controls SOC to keep the best fuel efficiency of the vehicle.
HEV which uses high voltage battery is equipped with a system that automatically shuts off the power from the main high voltage battery when a state of emergency occurs.
The state of emergency refers to undue short-circuits and insulation breakdown caused by short that occurs by aging of related components or undue short-circuits and insulation breakdown by components destruction from external shocks. When the state of emergency occurs to the vehicle, upper components controlling high voltage such as BMS or Hybrid Control Unit (HCU) controls a power source by transmitting an order to shut main power off.
Components related to high voltage shut main power off through Controller Area Network (CAN) communication or signal transmission when voltage or current exceeding normal range is detected, when leakage current and insulation resistance destruction are found to be more than allowance during monitoring voltage and current in the line for connecting power through a series of program or sensors.
These conventional technologies for securing safety in relation to a large volume battery for electric vehicles are designed for cases that a battery is used as the main power, but still are not equipped with any device to secure safety from short of the sensing line which monitors the status of batteries.
As described above, the battery is formed of several cells connected in serial and parallel so that it could have the power and storage capability desired by users, and all these cells used are monitored through BMS and is designed to take proper actions to prevent any accident when such an accident occurs or is concerned to occur. The system is called ‘active safety device’.
However, accidents do not always occur while the vehicle is under operation. Therefore, a device for preventing any accident occurring in a state that the vehicle is not under operation, i.e., a state that BMS is not started to operate, is required.
There are manual safety devices for this case. For example, provided are methods for attaching an auxiliary device to cut electrical connection off using the change of a battery s physical status, or mounting a large volume fuse on the main power line which provides electrical connection between a battery and an inverter. But for sensing lines, since a separate manual safety device is not prepared, there is a high possibility of a fire on sensing line when a short circuit accident occurs. Accordingly, the secondary fire (firing on the battery) and the tertiary fire (firing on the vehicle) are concerned to occur.